structure Error = struct

datatype error = 
	 Undeclared
       | TypeMismatch
       | ArgumentFail
       | ReturnFail
       | LvalFail

fun toString Undeclared = "Undeclared"
  | toString TypeMismatch = "TypeMismatch"
  | toString ArgumentFail = "ArgumentFail"
  | toString ReturnFail = "ReturnFail"
  | toString LvalFail = "LvalFail"




end
